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Biunpentium
Biunpentium, also known as eka-'[[Unhexpentium|'unhexpentium]] or element 215, is the temporary name of a hypothetical superheavy chemical element in the periodic table that has the temporary symbol Bup and has the atomic number 215. As of 2012, no attempt has been made to synthesize this element. Nuclear Properties What follows is based on a first-order, liquid-drop assessment of where the outer boundary of the nuclear world is. Assume cautious values for how many neutrons a nucleus with 215 protons can bind (high neutron dripline) and how few it can have before it fissions immediately regardless of how much the structure it can develop stabilizes it (low must-fission curve). Assume, too, that anything that lasts long enough so that protons and neutrons can be treated as particles rather than collections of quarks (is causal) might be a nucleus. Under these conditions, Bup isotopes are theoretically possible between Bup 645 and Bup 960 (see "The Final Element", this wiki). Bup 645 through Bup 757 are expected to decay by beta emission if they don’t fission quickly. Above that value of A, the confident neutron dripline, drops may decay by neutron emission before they can fission. (Structural correction does not affect neutron emission.) Isotopes lighter than Bup 677 need more than twice the structural correction energy needed to prevent fission in worst-case nuclei in the A = 480 region(3). Predicting whether or not the structure a nuclear drop can develop will allow it to survive for the 10^-14 sec required for it to bind an electron and so become an atomic nucleus is not usually possible at this time. Neutron shell closures have been predicted at N = 644, and 524(4). The former may allow some nuclei in the vicinity of Bup 859; it requires only 1.5 MeV structural correction, but is 13% above the confident dripline. The latter may allow some nuclei in the vicinity of Bup 739; it requires 10.5 MeV of structural correction, but lies below the confident dripline. The band Bup 729 through Bup 864 is the most probable location for Bup isotopes. Bup 676 and lighter are implausible, while Bup 865 and heavier are highly unlikely. FORMATION Ions of this element may form when material from roughly 1 km depth is ejected from a disintegrating neutron star during a merger. It is probably impossible for lighter isotopes to form in this way. 3. "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011. 4. "Magic Numbers of Ultraheavy Nuclei"; V. Yu Denisov; Physics of Atomic Nuclei, v. 68, no. 7, pp 1133-1137; 2005. (12-04-19) Chemical Properties Electron structure of Bup has not been studied closely, but it is likely to differ significantly from the conventional orbitals found in lower-Z nuclei. While only the innermost electrons would be qualitatively different, other electrons are likely to be quantitatively different from those in lower-Z atoms. Bup is also large enough that nuclear shape may have an effect on electron structure, which might cause different isotopes of Bup to be chemically different. (Which means it is no longer an element in the chemical sense.) Predictions of atomic or chemical properties of Bup are risky. (12-04-19) References Category:Undiscovered elements Category:Pnictogens Category:Radioactive